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Old 03 July 2013, 05:24   #1
merio
 
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Newbie needs help with an Amiga 600

I bought an Amiga 600HD recently and I'm unfortunately having a few issues.

It came with an RGB cable, when I got it home and tried it out just got black screen but then I tried using composite and it worked, I don't know whether it was a bad cable or is indicative/symptom of a greater problem.

Started playing a few games and it seemed fine, but a few disks in it became apparent that the top row of keys, Esc F1 etc. weren't responsive.

Also for games that need discs swapped, the second disc wasn't being recognized. (no monkey island or alien breed for me)

Read in another thread that taking out the keyboard connection and reinserting it might fix the unresponsive keys, tired this and no luck. When I opened it up to do this there was some sticky gunk stuff, something leaking maybe? but it was just on the plastic.

From what I gathered in the amiga problems sticky, this all seem to indicate something wrong with the CIA chips (apart from the RGB) and they need replacing.

Also gather that replacing these on a 600 is not very easy so just thought I would ask some advice, get an opinion and see if anyone could recommend a next course of action before I go ahead?

Cheers
 
Old 03 July 2013, 10:28   #2
demolition
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Sounds to me like you have a bad keyboard and a bad floppy drive. The floppy has a little switch to detect disk change and it could get stuck. You should be able to see it from the outside. It could also be that the signal does not reach the Amiga.

I don't think you need to replace a CIA chip. If that was the case, your disk drive would probably not be working at all.

Regarding RGB, it could be a broken cable or acid damage from caps inside the Amiga. Open up the DSUB connector and check that all wires are still connected.
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Old 03 July 2013, 11:09   #3
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If unsure, take a high resolution picture of the motherboard and I'm sure our experts here will be able to help you out
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Old 03 July 2013, 11:57   #4
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Sticky gunk stuff on keyboard connectors sounds like C324 and C334 have leaked, a mildly greenish / brown muck with fluff stuck in it and a smell like fish / urine.
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Old 03 July 2013, 13:35   #5
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Er, what monitor did you plug the RGB cable in? Few monitors handle 15khz, most start at 31khz.
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Old 03 July 2013, 13:55   #6
merio
 
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Thanks for the replys. Here's the motherboard pic.







and the gunk on underside of keyboard







Couldn't see the switch in the floppy drive and cable was RGB to scart plugged into a pal crt.
 
Old 03 July 2013, 14:10   #7
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Hard to see anything on the MB. Looks fine, but the pic isn't very high res so can be hard to see.

Try to make a close up pic of the area just south of the power connector where all the caps are close together. That's a usual place for leakage to occur. The solder pads on those caps should be shiny. If they are dull looking, you probably have some cap leakage, which could explain most of your symptoms as that will corrode and break tracks on the motherboard.

No idea what that gunk is on the underside of the keyboard. It looks like it touched something on the MB, but I can't see what it should be.
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Old 03 July 2013, 14:42   #8
merio
 
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Originally Posted by demolition View Post
Hard to see anything on the MB. Looks fine, but the pic isn't very high res so can be hard to see.

Try to make a close up pic of the area just south of the power connector where all the caps are close together. That's a usual place for leakage to occur. The solder pads on those caps should be shiny. If they are dull looking, you probably have some cap leakage, which could explain most of your symptoms as that will corrode and break tracks on the motherboard.

No idea what that gunk is on the underside of the keyboard. It looks like it touched something on the MB, but I can't see what it should be.


Sorry is pics aren't clear best I can do I'm afraid.







Everything looks pretty shiny and clean to me to be honest, can it be quite subtle or is it more obvious when a cap leaks?
 
Old 03 July 2013, 14:42   #9
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Top left black thing is the switch we are talking about

http://en.academic.ru/pictures/enwik...motor_open.jpg

The board looks to be in good condition, usually the part marked as 4R7 has green / black legs in badly corroded units.

Last edited by Loedown; 03 July 2013 at 14:44. Reason: post in between
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Old 03 July 2013, 14:52   #10
merio
 
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Top left black thing is the switch we are talking about
Cheers, just tried a disk and it's pushing down fine as far as I can tell.


The gunk (glue?) seems to have emanated from the around the HD somewhere as I've just noticed it's on the the little arms of the mount, HD has worked fine though so a little confused tbh.

Last edited by merio; 03 July 2013 at 14:58.
 
Old 03 July 2013, 15:39   #11
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You can check in workbench if the floppy works.. insert a disk, it should show its icon on workbench. Without opening it, remove the disk. The disk icon should then go away.

The sensor can get a bit stuck sometimes. Just press it down a few times with something flat and it usually starts working again, if its the problem. The floppy disk does not press down as much on it as you can manually.
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Old 03 July 2013, 15:48   #12
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Quote:
Originally Posted by merio View Post
The gunk (glue?) seems to have emanated from the around the HD somewhere as I've just noticed it's on the the little arms of the mount, HD has worked fine though so a little confused tbh.
Maybe there was some tape or rubber at the top of the arms which have dissolved over the years. Just clean it off, and I don't think it has anything to do with the other problems.
There's no obvious cap leakage visible on those pics, but that doesn't mean it's not there. Some times you'll find a single via being very corroded, even though it's far away from any caps. Most 600s need new caps by now if they haven't had it before (and few have).
If it was my 600, I'd replace all the electrolytic caps with new ones, and before putting the new ones in, I'd look very closely on the entire PCB, looking for dull looking solder pads and vias or other out-of-place things. Some times you need to repair some tracks, and usually better to do that before putting in the new caps.
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Old 04 July 2013, 11:10   #13
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Ok, thanks alot for your help guys, I'll try your suggestions.
cheers

Last edited by merio; 06 July 2013 at 08:05.
 
Old 06 July 2013, 08:05   #14
merio
 
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***update***
Pushing the switch in the floppy has fixed the disc issue, so many thanks for the info
I've looked over the whole MB and it looks really clean to me and I can't see any dullness or corrosion anywhere.
It seems odd to me that only the top row of keys aren't working if there was damage on the MB in regards to the keyboard wouldn't it not work all together, rather than just the top row of keys?
I opened up the keyboard to give it a clean and it seemed fine, the plastic was a little warped but screwed down nice and tight.
Has anyone had the same keyboard issue?
Is there anyway to map the unresponsive keys to another key combination or get around having no F-keys?
 
Old 06 July 2013, 08:34   #15
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@merio

The keyboard is arranged in a matrix/grid, so you have many paths on the motherboard and only some of them might be broken, in this case the ones that are connected to the top row of keys. If you look at the schematics of the A600, page 6, you'll see how it's arranged. If you know your way around a multimeter, you could check the connections one by one and maybe find out where the problem is.
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Old 06 July 2013, 08:47   #16
merio
 
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@merio

The keyboard is arranged in a matrix/grid, so you have many paths on the motherboard and only some of them might be broken, in this case the ones that are connected to the top row of keys. If you look at [url= schematics of the A600[/url], page 6, you'll see how it's arranged. If you know your way around a multimeter, you could check the connections one by one and maybe find out where the problem is.
Ah right, cheers for that.
As you can probably tell, this is my first time even opening a computer apart from changing the fans in my PC, I might have to try and find someone local who can give me a hand.
 
Old 06 July 2013, 08:51   #17
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Yeah, you don't normally need to fix things at this level with modern stuff There are plenty of people on this board (and perhaps on Amibay) who can do fault finding and repairs on Amigas, so that is probably your best bet.
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Old 06 July 2013, 10:06   #18
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The common connection for the top row of keys is pin 1 in the keyboard connector, so that is probably where the problem is.

You can see the schematic on page 16 here:
http://www.amigawiki.org/dnl/schematics/A600_R1.5.pdf

I'm guessing its the keyboard ribbon where it connects onto the motherboard. I don't know if you already did, but to detach the ribbon you lift the header and it will release. Reverse to install. Some people pull out the ribbon while the header is locked and that will quickly ruin the connections.

Some people had luck in cutting off a very thin slice of the end of the ribbon (less than 1mm) to create contact with a fresh part of the ribbon. Just remember that if you're unsuccesful with this, you might lose all functionality in the keyboard.
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